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R. H. ST. JOHN.

TENSION FOR-SEWING MACHINES.

(Nq Model.)

Patented Feb. 23, 1886.

N PETERS. Fhnlo Lllhognphen Washington. D. (:.Y

UNITED STATES PATENT Orrrcn.

ROSWELL H. ST. JOHN, OF TOLEDO, OHIO, ASSIGNOR TO THE UNIONMANUFACTURING COMPANY, OF SAME PLACE.

TENSION FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 336,827, dated February23, 1836.

, Application filed October 16,1884. Serial No. 145,666. (X0 model.)

To all whom itmay concern/.-

Be it known that I, RoswELL H. ST. JOHN, of Toledo, in the county ofLucas, and in the State of Ohio, have invented certain new and usefulImprovements in Tensions for Sewing- Machines; and I do hereby declarethat the following is a full, clear, and exact description thereof,reference being had to the accompanying drawings, making a part of thisspecification, in which- Figure 1 is a perspective View of the parts ofmy improved device separated from each other. Fig. 2 is a like view ofthe same in place upon a sewing-machine, and Fig. 3 is a side elevationof said device.

Letters of like name and kind refer to like parts in each of thefigures.

The object of my invention is to increase the efficiency of theupper-thread tension of a sewing-machine; and to this end said inventionconsists, principally, in a sewing-machine tension composed of aspring-plate that rests upon and is held with a yielding pressureagainst a pivoted bearin g, which is adapted to rock in a plane that isparallel with the line of draft, substantially as and for the purposehereinafter specified.

It consists, further, in a sewing-machine tension composed of aspring-plate which is supported at one end upon a fixed bearing and atits opposite end rests upon and is held with an adjustable pressureagainst a pivoted rocking bearing, substantially as and for the purposehereinafter shown.

It consists, further, in a sewing machine tension composed of anadjustable pressureplate superimposed upon a rocking bearing, which, bymeans substantially as shown, has its motion limited, substantially asand for the purpose hereinafter set forth.

It consists, finally, in the construction and combination of part-ssubstantially as and for the purpose hereinafter shown and described.

In the annexed drawings, A represents the horizontal portion of thestationary arm of a sewing-machine,from the upper side of which, andforming a part of the same, three bosses, a, a, and a, respectively,extend upward from equidistantpoints. The rear boss, a, has, preferably,a height of about three-fourths of an inch, and is provided Within itsupper end with a horizontal groove, (1 The central boss, a, has a heightof about one-half an inch, and is provided with a central verticalopening, a, that is threaded, while the third boss, at, has a height ofabout one-half an inch, and is provided with a horizontal transverseopening, a".

Pivoted upon the boss a is a flat bearing, B, which is preferablyconstructed from sheet metal, with two opposite downwardly-turned ears,b, that embrace the sides of said boss, and through which and throughthe opening a passes a pivotal screw, 0. From the rear edge of saidbearing an arm, 1), extends rearward and downward, and has its outer endcontained within a notch, a, that is formed in the contiguous side ofthe central boss, a. Said notch has preferably such vertical dimensionsas to permit the engaging end of said arm to move about one-sixteenth ofan inch in such direction before the motion of said bearing is arrested.

Resting upon the bearing B, and within the groove a of the boss a, is aflat spring-plate, D, that is provided with a central opening, d,through which the threaded body of an adjusting-screw, E, passesdownward into the.

threaded opening a". Between said opening d and the front end of saidplate is a second opening, d, from which a slot, d, extends diagonallyrearward and outward, as shown.

The device thus constructed is used as follows, viz: Thread f, from aspool, F, is passed through the slot, d into the opening (1, and fromthe same passes forward between the plate D and bearing 13, and thenceto the needle. By means of the screw E the pressure upon the thread andthe consequent resistance offered to its passage between the impingingsurfaces may be regulated at will. Should a lump or knot exist in thethread, it will readily pass between the pressure-surfaces withoutmaterially altering the tension, as at its entrance between, and untilit reaches the center of said surfaces, the bearing B will rock downwardat its rear end, and as said knot passes forward of the center will rockforward and downward, thus accommodating itself to the position of saidknot, and enabling said spring-plate 1) at all times to have a bearingupon the said thread upon one or the other side of the obstruction.

Having thus fully set forth the nature and merits of my invention, whatI claim as new 1s 1. In combination with the pivoted bearing B, providedwith the arm I), the boss (0, provided with a notch limiting theup-anddown play of the arm, and so the swing of the bearing in bothdirections 011 its pivot, sub stantially as and for the purposedescribed.

2. In combination with the spring-plate provided with a suitablethread-opening, the

boss a supporting the rear end of the plate, I5 the boss a and thepivoted bearing B thereon, having arm 12, the boss a, having notch a,eugaging the end of such arm, and the thumbserew passing down throughthe spring-plate and tapped into the boss at, substantially as 20 andfor the purpose described.

In testimony that I claim the foregoing I have hereunto set my hand this13th day of November, A. D. 1883.

OSXV ELL H. ST. JOHN.

Vitnesses:

ASHTON H. Conn-mu, RATHBURN FULLER.

